Anesthetics

Question 1

Goal of general anesthesia

Answer 1

amnesia
analgesia
immobilization

Question 2

Inhaled anesthetic properties

Answer 2

cross BBB

Lipid solubility - higher = more potent

blood solubility - lower = more rapid onset of action
-doens’t get “stuck in the blood”

Question 3

Minimum alveolar concentration (MAC)

Answer 3

concentration of inhaled anesthetic needed to prevent movement in 50% of patients after painful stimulus

Question 4

Inhaled anesthetic drugs

Answer 4

Nitrous oxide

• low blood solubility (rapid induction), low lipid solubility (low potency)
• block NMDA receptors
• rapid onset/rapid recovery

Halothane

• high blood solubility (long induction)
• hepatotoxicity
• long to start, long to recover

Sevoflurane, desflurane

• low blood solubility, high lipid solubility
• potent, most used

Isoflurane
-moderate blood and lipid solubility

Question 5

Propofol

Answer 5

IV anesthetic

increases GABA
Rapid onset, rapid recovery (20-40min)
high triglyceride count - risk acute pancreatitis with prolonged use

“milk of amnesia”
maintenance in IV drip

Question 6

Ketamine

Answer 6

IV anesthetic

dissociative anesthetic
hallucinations in high doses in adults
increases cerebral blood flow

use: analgesia, conscious sedation, induction

Question 7

Barbiturates

Answer 7

IV anesthetics

Phenobarbital - increases liver enzyme synthesis (used in Crigler Najjar type II)
Pentobarbital
secobarbital
Thiopental (important in brain surgery)

increase duration of Cl- channel opening on GABA receptors

SE:
sedation, CNS depression, sluggish, ataxic gait, double vision

Overdose: tx sx, no antidote

Question 8

Benzodiazepines

Answer 8

IV anesthetics

Diazepam
lorazepam
alprazolam
Midazolam - MC used for conscious sedation

Others:
Temazepam - insomnia - long acting
Chlordiazepoxide - etOH withdrawal

Increase frequency of Cl- channel opening on GABA receptors

Reverse w/ flumazenil (can trigger withdrawal seizure)

Question 9

mnemonic for barbiturate and benzodiazepine MOA

Answer 9

“Ben likes it more frequently, Barb likes it to last longer”

effects on Cl- channel on GABA receptors

Question 10

Opioids used as IVE anesthetics

Answer 10

morphine
fentanyl (doesn’t induce histamine release, not as itchy as with morphine)
remifentanil
sufentanil

Analgesia

mu, delta, kappa receptors

Question 11

Butorphanol

Answer 11

partial opioid

causes respiratory depression

Question 12

Dextromethorphan

Answer 12

weak opioid used for cough suppression

Question 13

Tramadol

Answer 13

less addictive opioid used for analgesia

Question 14

Loperamide, diphenoxylate

Answer 14

treatment of diarrhea

Question 15

Naloxone, naltrexone

Answer 15

opioid receptor antagonists

reverse opioid overdose

Question 16

Endogenous agonists of mu, delta, kappa receptors

Answer 16

Mu - beta-endorphin
Delta - enkephalin
Kappa - dynorphin

Question 17

Non-depolarizing NM blocking agents

Answer 17

tubocurarine
atracurium
mivacurium
vecuronium
rocuronium
pancuronium

Competitive inhibitors of postsynaptic nicotinic acetylcholine receptors at NMJ

can reverse w/ acetylcholinesterase inhibitor - neostigmine

Question 18

Depolarizing NM blocking agent

Answer 18

succinylcholine

causes muscle fasciculations

Phase 1: rapid onset and recovery, cannot be reversed - 10 min

Phase 2: larger dose, longer recovery - can be reversed w/ AChEI - lasts 20-30 minutes up to hours

Succinylcholine + inhaled anesthetic in patient with RYR1 gene mutation –> malignant hyperthermia
Tx: cool patient, sedate, dantrolene (block release of Ca2+ from SR)

Question 19

Local anesthetics

Answer 19

Lidocaine, procain, cocaine
block Na+ channels

Don’t work well in acidic tissues - infected tissues

give w/ local vasoconstrictor (epi)

• except in terminal organs (eg fingers - no collateral circulation = ischemia)
• don’t need as much anesthetic, reduces bleeding

Question 20

Order of blockade for local anesthetics

Answer 20

small myelinated
small unmyelinated
large myelinated